1. Field of the Invention
This invention relates to electrical connector assemblies in which multiple electrical connections are made between two connector blocks when the blocks are brought together, and more particularly to such assemblies that employ a jackscrew to bring the two blocks together in mutual alignment.
2. Description of the Related Art
Electrical connector assemblies are widely employed when relatively large numbers of electrical connections are to be made at the same time. The assemblies typically employ a pair of connector blocks, one with an array of male contacts and the other with a matching array of mating female contacts. Each male contact extends into a corresponding female contact when the two blocks are brought together, thereby establishing the desired pattern of electrical connections. Of course, it is important that the connector blocks be properly aligned with each other during the assembly process.
A connector assembly is described in U.S. Pat. No. 3,281,761 to Moulin, assigned to Hughes Aircraft Company, the assignee of the present invention, which automatically aligns the two connector blocks with each other as they are brought together. This is accomplished with a jackscrew coupling in which a jackscrew on one of the blocks screws into a threaded receptacle on the other block, drawing the two blocks together as the jackscrew is progressively screwed in. An alignment between the two blocks is achieved by means of keying sections or tines that extend from the two blocks towards each other around the outside of the jackscrew. The tines from each block are separated by notches into which the tines from the opposite block can be inserted. The tines and notches are made non-symmetrical, permitting the two blocks to be fully assembled only when they are properly aligned; in other orientations the two sets of tines hit each other, preventing further rotation of the jackscrew to bring the blocks together.
While the connector assembly described in the '761 patent represents a distinct improvement, it still has some serious limitations. Its various parts are made of metal to withstand the axial forces imposed by the rotation of the jackscrew into the threaded receiver on the other block. Metal parts, however, add significantly to the device's cost and weight, and require very close machining tolerances. Furthermore, the mechanism for securing the jackscrew to the first connector block involves crimping a portion of an annular collar around a flange on the jackscrew. This is a cumbersome operation, and can result in interference with the jackscrew rotation if the crimp is too tight, or a possibility of the jackscrew coming out if the crimp is too loose.
Other electrical connector assemblies that employ jackscrews to bring together a pair of connector blocks are described in U.S. Pat. No. 4,934,950 to Green et al., and U.S. Pat. No. 4,627,759 to Kato et al. In the '950 patent a jackscrew nut is mounted over the rear portion of a jackscrew in a male connector block, and held in place by a roll pin that is inserted in an interference fit through aligned holes in the pin and jackscrew. The nut is slotted so that it can be rotated by a screwdriver to rotate the jackscrew. The jackscrew, however, does not project into the opposite connector block. Rather, a free standing key member on that block includes a threaded interior opening that engages the jackscrew threads, with the key member drawn into a keyed opening surrounding the jackscrew in the first connector block as the screw is rotated. Furthermore, the various parts are made of metal, with the attendant cost and weight drawbacks discussed above. In the '759 patent a taper is cut into the middle portion of the jackscrew, which is held in place on its connector block between a conventional screw head and a stopper that is retained in the tapered portion. The jackscrew is thus intentionally weakened, so that it breaks before either the connector housing or the jackscrew threads are damaged in case of over-tightening. The jackscrew is required to be first inserted into the connector block from the rear, and the stopper then put in place over the tapered portion of the screw shaft. This operation is made difficult by the presence of a chamber which surrounds the front end of the jackscrew for the purpose of receiving a nut on the opposite connector block, which receives the jackscrew.